Radio images reveal fast-moving electrons interacting with the galaxy’s magnetic field. They help us map atomic and molecular hydrogen and hot ionized regions.
Infrared images show where starlight heats the interstellar gas and dust and reveal red giants, planetary nebulae, and young, massive stars deeply embedded in their parental molecular gas clouds.
Visible light shows us relatively nearby stars because interstellar dust obstructs our view of more distant ones.We can also see dark patches where clouds of gas and dust block starlight.
X-rays and gamma rays uncover energetic regions. X-rays are produced by hot, shocked gas. Gamma rays primarily come from high-speed particle collisions.